Manufacture of alkyl fluorides



Patented Nov. 1940 PATENT orFlcE 2,220,713 MANUFACTURE or ALKYL FLUORIDES Aristid V. Grease and Charles L. Thomas, Chicago, 111., assignors to Universal Oil Products Company, Chicago, 11]., a corporation of Delaware No Drawing. Application February 25, 1938, Serial No. 192,499

- Claims.

This invention relates more particularly to a process for the manufacture of alkyl fluorides by the direct addition of hydrogen fluoride to aliphatic olefins and cyclo-oleflns.

5 Alkyl halides have found various uses in chemiis considerably easier to addhydrogen iodide to i an olefin such as hexene than it is to add hydrogen bromide, hydrogen chloride, or hydrogen 15 fluoride in the order named. In the case of ethylene, hydrogen fluoride combines only with c0n' siderable diificulty and the present invention is concerned with a process for combining the olefins of higher molecular weight than ethylene with hydrogen fluoride. Some previous methods employed for the. manufacture of alkyl fluorides, particularly those of low molecular weight, consisted in reacting alkyl iodides with silver or mercury fluorides and reacting hydrofluoric acid with alcohols. However, these methods are somewhat tedious and give only small yields of the desired fluorine compounds.

In one specific embodiment th present invention comprises a process for the production of alkyl fluorides from oleflns of higher molecular weight than ethylene and from cyclo-olefins which comprises reacting the unsaturated compounds with hydrogen fluoride at minimum temperatures such as, for example, those comprised within the approximate range of 25 to -60 C.

in the case of the aliphatic compounds.

The actual operation of the process will depend to some extent upon the phase of the hydrocarbons treated. In the case of the normally gaseous oleflns including propylene and the hutylenes, the simplest procedure in a batch operation is to add hydrogen fluoride to a pressure reactor and then add the olefln at a rate dependent upon the speed of the reaction as indicated by the drop in pressure in. the pressure vessel. When utilizing the low temperatures specified, side reactions leading to the polymeri zation of the 'oleflns is substantially eliminated so that increased yields of the desired alkyl or 60 aryl fluorides are obtained. Continuous opera-' tions may be conducted by simultaneously injecting hydrogen fluoride and an olefln hydrocarbon into a cooled reactor while continuously separating the reaction products by low temlo perature fractionation or by the action 0! specal methods.

ciflc absorbents or. solvents or by any other chemi- The details of such processes are more or less common-practice and any suitable procedure may be utilized without departing from the scope of the invention. 6 When fluorides of normally liquid unsaturated hydrocarbons are desired, such compounds as hexenes or cyclo-hexene may be cooled to a suitable low temperature and treated simultaneously with proportioned mixtures ofvhydrogen fluom ride either in batch or continuous processes. Itis obvious that conditions of treatment will require modification in the case of difierent unsaturated hydrocarbons which will vary in their activity'with their structure and their molecular 15 weight, so that only general ranges of temperature, and the amount and proportion of hydrogen fluoride can be stated. As a rule only a small excess of hydrogen fluoride is necessary, of the order of about1.25'moles.

The following examples are given to illustrate the results normally obtained by the process of the invention although not with the intention of unduly limiting its scope.

' Example I 25 Using a nickel lined pressure vessel equipped with a mechanical stirring device, 200 parts by weight of anhydrous hydrogen fluoride were added under pressure at a temperature of 30 C. .0 Propylene was then continuously added to maintain a pressure of approximately lbs. per square inch until there was a marked pressure rise on a further addition which indicated the completion of the reaction. It wasfound that 35 this point corresponded to the addition of one molecule of propylene for each one and one-half molecules of hydrogen fluorides. At the completion of the reaction the contents of the pressure vessel were released and fractionated at low temperatures for the recovery of propyl fluoride which was found to have been produced in a yield of about 75% of the propylene added. There was some production of high boiling polymers which were readily separated. 5

Example II Into a. pressure vessel supplied with an effective stirring device, 169 grams of anhydrous hydrogen fluoride were introduced by the method the temperature being held below 0 C. by cooling. since the reaction was exothermic. 66f

Charge, 220 grams d =0.943 Pressure=2 mm.

B. P. Weight, ,5 Fraction range grams d N Color 1 51 47 91 1. 4170 Water white. 2 51-91 21 92 1. 4748 Do. 3 91-120 4 1. 4799 Amber. Bottoms 120 145 Dark red.

Fraction 1 from the above distillation was redistilled at 100 mm, pressure and the following table shows the results of thisdistillation. The fractions 3A, 4A, and 5A corresponded closely to the physical constants for fluorocyclo-hexane.

Charge, 23.4 grams Pressure, 100 mm.

B. P Weight, Fraction range grams d N M. P

'a=g=0.925s.

The character of the invention is clearly shown by the above specification and numerical data neither of which is intended to be unduly limit- 45 ing.

We claim as our invention:

1. A process for producing alkyl fluorides from olefins of higher molecular weight than ethylene which comprises reacting theolefln with hydrogen fluoride at a temperature below 0 C.

2. A process for producing allwl fluorides from aliphatic olefins of higher molecular weight than ethylene which comprises reacting the olefin with hydrogen fluoride at a temperature within the approximate range of -25 to -60 C.

3. A process for the manufacture of propyl fluoride which comprises reacting propylene with hydrogen fluoride under super-atmospheric pressures and at temperatures below. 0 C.

4. A process for the manufacture of butyl fluoride which comprises reacting a butylene with hydrogen fluoride under super-atmospheric pressures and at temperatures below 0 C.

5. A process for producing alkyl fluorides from normally gaseous aliphatic olefins of higher molecular weight than ethylene which comprises reacting the olefin with hydrogen fluoride at a temperature within the approximate range of 6. A process for the manufacture of propyl fluoride which comprises reacting propylene with hydrogen fluoride under superatmospheric pressures and at temperatures within the approximate range of to -60 C.

7. A process for producing propyl fluoride which comprises reacting propylene with hydrogen fluoride at a temperature within the approxi mate range of 25 to -60 C.' r

8. A process for producing butyl fluoride which comprises reacting a butylene with hydrogen fluoride at a temperature within the approximate range of -25 to -60 C.

9. A process for producing cyclo-alkyl fluorides which comprises reacting a cyclo-olefin with hydrogen fluoride at a temperature below 0 C.

10. A process for producing fluorocyclo-hexane hydrogen fluoride'at a temperature below 0 C. which comprises reacting cyclo-hexene with hydrogen fluoride at a temperature below 0 C.

/ f ARISTID V. GROSSE. CHARLES L. THOMAS. 

